Various fuels burned in the utility boiler produce residue. This residue collects on the walls of the chamber in which the combustion takes place. There is an ongoing problem of removing this solid residue of combustion. The burning of pulverized coal as a fuel leaves the largest amounts of solid residue behind for disposal.
In addition to the problem of removing solid residue from the bottom of the combustion chamber, there is the problem of the fly ash carried over into the back-pass to which the combustion chamber discharges. The temperature of the combustion gases is reduced as they flow into heat exchange contact with structures mounted in the back-pass. The temperature of the combustion gases, typically within the 1000.degree. F. to 1200.degree. F. range, may reduce to the range including 800.degree. F. after initial contact with the economizer mounted in the back-pass. The fly ash sinters within this temperature range and gravitates into impact upon surfaces of the back-pass which change the direction of the combustion gas flow. As the fly ash sinters into an enlarging body, it may actually become an obstruction to the flow of combustion gases in the back-pass.
The problem addressed by the present invention is continuous removal of the collected fly ash from the 800.degree. F. environment. A mechanism must be applied to continuously quench the fly ash and periodically remove the collected fly ash. Preferably, liquid is to be applied as an agent to purge the plate surface upon which the fly ash collects.